This study deals with boarding/alighting congestion of congested commuter train stations at central business district (CBD), in which the additional fares are determined to shift an appropriate number of passengers to board/alight at the neighboring uncongested stations on the railway line. A bi-objective model is investigated to minimize both fare increases of the congested stations, while alleviating their boarding/alighting congestion to a certain level simultaneously. The existence of the unique Pareto-optimal solution is proven mathematically in the absence of explicit demand functions. A trial-and-error fare design scheme is proposed to identify the Pareto-optimal solution. An illustrative study demonstrates the effectiveness of the trial-and-error scheme.